Generating Electricity Physics 1 GCSE ScienceChapter 10

Energy– the problem with using too much Where do we get most of our energy from? Oil Coal Gas Environmental problems! (Atmospheric pollution and climate change) GCSE ScienceChapter 10

What happens to the Earth? Global Warming Earth’s Atmosphere Sunlight travels as electromagnetic waves through space and the atmosphere, towards the Earth. A proportion of this energy is absorbed, and a part of it is reflected. When the Earth radiates the absorbed heat energy back into space, it is in the form of infra- red radiation with a longer wavelength. Some molecules, such as carbon dioxide and methane, absorb some of this longer wavelength radiation, and trap the energy within the atmosphere. Consequently the atmosphere heats up – this is known as the Greenhouse Effect. GCSE ScienceChapter 10

The Effect of Global Warming What will the effect of a temperature rise of 2°C be? More deserts – less land to grow crops. Change in climate – more extreme weather, floods and drought becoming common. Winters will be warmer The sea level will rise as a result of polar ice caps melting. The Gulf stream’s direction could change and as a result, Britain’s temperature would fall. Our carbon dioxide emissions is responsible for this, and there is a constant campaign to get us to burn less coal, oil and gas. GCSE ScienceChapter 10

The Energy Crisis Coal, oil and gas are examples of non- renewable resources. Oil Coal Gas After using them once, you cannot re-use them – you would have to wait millions of years for them to be produced. By 2020 we in Britain will have to reduce our dependence on coal, oil and gas and produce electricity by renewable means. GCSE ScienceChapter 10

Thermal Power Stations turbine generator Hot water condenser Cold water Water Steam Hot steam Cooling tower steam Cold water boiler Coal, oil or gas Fossil Fuel 1. Burning Fossil Fuels 2. Cold water turned into steam in the boiler. 3. Steam turning the turbine 4. Turbine turning the generator and producing electricity. Cold steam 5. Part of the energy is lost to the environment at this stage. It’s possible to use the waste steam to heat the factory or nearby houses. GCSE ScienceChapter 10

National grid Condenser Cold Water Turbine Generator Heat Hot steam Hot water The latest power stations use the hot water to heat up the surrounding houses. Is it possible to improve the design? It’s possible to use wood as fuel. New trees can be planted and grow quickly to replace the fuel supply. These trees absorb CO 2 as they grow and release it when they burn – so no net gain or loss of CO 2. GCSE ScienceChapter 10

Thermal Power Station turbine generator Hot water condenser Cold water Water Steam Hot steam Cooling tower steam Cold water Nuclear 3. Steam turning the turbine 4. The turbine turning and generating electricity. Cold steam 5. At this stage, part of the energy is lost to the environment. Cooler corefuel Steam generator 2. The steam generator turns cold water to steam 1. A nuclear reaction in the core. One nuclear station is equal to 2400 wind turbines! GCSE ScienceChapter 10

Start up time The different types of power stations have different ‘preparing to start’ times: Fast Slow Gas Oil Coal Nuclear Oil GCSE ScienceChapter 10

Non-renewable Energy Sources Coal, oil, gas and nuclear Advantages Disadvantages Low fuel costs Good for meeting basic energy requirements Fuel supplies depleting Nuclear energy creates very little pollution High commissioning and decommissioning costs in a nuclear power station Gas and oil have a low start-up time Pollution – CO 2 leads to global warming and SO 2 to acid rain Dependable GCSE ScienceChapter 10

Renewable Energy – Wind Power Wind turbines are a familiar site in this country. The sites are called ‘wind farms’. Strong winds in Britain mean that this is a viable source of energy production for us. However, some are against this. They claim that the wind turbines destroy habitats, that they are noisy and ineffective. GCSE ScienceChapter 10

Renewable Energy – Tidal Power Low Tide High Tide As the tides turn, the movement of the water turns the turbine, and the generator produces electricity. GCSE ScienceChapter 10

Renewable Energy – Wave Power The movement of the waves causes the float to move up and down. This turns the generator and it produces electricity. GCSE ScienceChapter 10

Renewable Energy – Hydro-Electric Power and Pumped Storage High resevoir When electrical energy is needed urgently, this hydro-electric system is used. Water form a high resevoir is released and as it flows, it turns the turbine and produces electricity. It depends on gravity. In a pumped storage scheme, an electrical pump can be used to pump the water back into the resevoir at off-peak rates, and so it can be re-used. GCSE ScienceChapter 10

SourceDisadvantage Wind Waves Tide Hydro-electric Also, the above have a long start-up time Weather-dependent; can be perceived as being an eye-sore by some; difficult to store. Can be harmful to marine life; dependent on the size of the waves; weather-dependent. Depends on the size of the tide and can affect habitats if mud flats are not uncovered for birds to feed. Habitats suffer due to flooding of river valleys in some schemes. Are there disadvantages to using renewable sources? GCSE ScienceChapter 10

Renewable Energy Sources Wind, tide, hydro- electric and solar Advantages Disadvantages No pollution Hydro-electric good for urgent demand for electricity Solar is good for remote areas (e.g. satellites) No fuel costs Unreliable (except Hydro-electric) Expensive to build Tidal barriers destroy bird habitats and hydro-electric depends on flooding farm land GCSE ScienceChapter 10